I am making the cupcakes for my wedding this weekend. I baked them all and put them in the freezer last week. Last night I made up a batch of Wilton buttercream icing to start decorating the cupcakes but when I piped it on my cupcakes there were so many air bubbles and the edges of the icing looked cracked (if that makes sense). I've always used the Wilton recipe and I have never had any issues. Help! Any ideas why it would do this?

I've found that  mixing the icing at the lowest possible speed and for the shortest amount of time possible creates less air bubbles.  But even then, they show up.  I let the icing sit for maybe 1/2 hour to an hour, and then I fold the icing over and over (and over and over) with a spatula until I see that the icing looks smoother. 

I"d also like to add that I use the paddle attachment on the kitchenaid rather than a hand mixer or the whip attachment.  The more icing in the bowl, the better.  It should reach up to the top of the paddle so that there is no space at the top of the paddle.  The space would allow air to whip into the icing.  Again, there are still air bubbles but less.  AND the softer the butter, the better. 

Part of your problem is the recipe you are using.  Try this one: http://www.cakecentral.com/recipe/22469/2-icing

I do things a bit differently than the other poster.  I found that long, slow mixing results in a smooth and creamy icing even when the beaters are not completely covered.  Good luck and happy marriage :)